It is known to install such analyzer systems in central or non-central laboratories. If analysis is performed in a central location within the processing plant, then samples must individually be taken from the process and transported by somebody into the laboratory for feeding into the analyzer system. However, during transportation the state of the sample can change. It is also disadvantageous that there is an unavoidable time delay between taking the sample and analysis. It is also disadvantageous that only individual samples can be analyzed, so that only stochastic measurements are possible. Attempts have therefore been made to install and operate the analyzer system in situ, which offers the possiblity of using process analyzers for continuous analyses and the measuring process can be both continuous and discontinuous with finite measuring cycles. It is known for this purpose to house the system in a fixed, walled or transportable container-comprising structure called "an analyzer shelter". Such a transportable analyzer shelter is described e.g. in a brochure entitled "Analyzer Shelter", issued in November 1981 by Benke Instrument and Elektro AG, of Pratteln, Switzerland. These analyzer shelters can be entered for the purpose of servicing and maintaining analyzers and auxiliary equipment. Although they are ideally suited for many applications, such relatively large-volume arrangements can also have disadvantages.
One of the disadvantages is that complicated and costly precautions have to be taken in view of the hazardous and health-prejudicial materials. The protection costs are much higher than e.g. in the case of instrumentation means, merely processing electrical signals. For the latter it is virtually merely necessary to have an adequate explosion protection and possibly a protection against the penetration of the external atmosphere.
Process analyzers or installation in an area where there is an explosion risk must satisfy the protection types and construction features indicated in the explosion protection regulations, which appear in the following industrial standards: VDE 0 165, 0 171; EN 50014 to 50020, 50028, 50039 and IEC 79-10.
Furthermore, process analyzers must for measuring reasons be protected against environmental influences in order to ensure measuring accuracy, stability and reproductivity of the measurements and to obviate premature aging of the electronic components. For economic and safety reasons apart from protection against the weather, it is also necessary to protect against aggressive or corrosive atmospheres.
In practice, protection is achieved in that separate explosionproof analyzers are placed in analyzer shelters and attempts are made to ventilate the shelters, which attempts have hitherto been very inadequate or involved considerable expenditure. Therefore, analyzer shelters are often only ventilated by natural ventilation. In the case of shelters containing several analyzer systems, a forced ventilation by explosionproof fans is also known. For forced scavenging purposes, for economic reasons air is taken out of the environment and must be cleaned, filtered, dried and treated as a function of its state. It is frequently also necessary to monitor for threshold-exceeding values of explosive and/or toxic mixtures, e.g. sulphur compounds. These measures are not only costly but are subject to a risk of unsatisfactory operation. Air scavenging also does not free the user from having to use explosionproof analyzer systems, in order to protect the same with respect to external expolosion risks and protect the environment against explosions, which could result from the ignitable materials in the analyzer system.
Even in the case of external ventilation of an analyzer shelter, particulary if there are several analyzer system possible exit quantities of flammable materials will lead to the lower explosion limit of the air/gas mixture being exceeded. The disconnection of the remaining analyzer systems and all electrical equipment in the shelter necessary for safety reasons is in most cases not acceptable for practical uses.
It is therefore unavoidable that the individual analyzers must be of an explosionproof construction. Possible explosion protection types are oil encapsulation, overpressure encapsulation, sand encapsulation and pressure-resistant encapsulation for increased security and intrinsic safety.
It is disadvantageous that, as a result of the mechanical construction of the explosion protection means, particulary in the case of pressure-resistant encapsulation, the accessibility to the internal components of the analyzer is impeded. This leads to long repair times and to low apparatus availability. In addition, fault detection is very complicated, because after opening the explosion protection means the analyzers must either be put out of operation or, because instead of this, it is constantly necessary to check the environment to ensure that it is free from explosion risks. A third complicated possibility is to ensure accident-free repairs or fault detection by special work protection, e.g. by a "hot work approval". A further disadvantage is that signal line passages through a casing with pressure-resistant encapsulation are subject to limitations in their numbers and all the signalling means for the remaining units of the analyzer system must have explosion protection. If an evaluation computer is provided, the latter must also be explosionproof, which once again leads to considerable technical and costly precautions.
Another disadvantage of an analyzer system with an analyzer shelter is that the point of installation cannot be freely selected as a result of the size of the system. As it is possible to enter an analzyer shelter, escape routes must also be kept free for staff. For safety reasons, access by a member of staff can only take place if somebody else is available for supervision and providing assistance in the case of an emergency. Thus, the analyzer system cannot be located in the vicinity of the process to be analyzed and therefore long supply lines and pumping equipment must be provided. As a result of the necessarily occurring clearance volumes and idle times, this is disadvantageous for measuring reasons.
Thus, the known analyzer systems have not been used to the extent and at the locations within a process, such as would be desirable for economic and measuring reasons.
BRIEF SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a novel and improved analyzer system which can be economically manufactured and operated and whose availability is improved.
According to the present invention there is provided in a self-supporting and sealed housing at least one extractable support member largely taking up the interior of the housing, the support member is connected at its front side with a first door member closing the extraction opening, and carries at least one process analyzer, at least one sample preparation means, at least one auxiliary material system and an unidirectional or bidirectional communications means for electrical signals, the support member being connected via flexible supply and disposal lines with the stationary housing part, access to the housing is provided with a door closing means coupled via monitoring means to an explosion and/or environment protection means in such a way that opening is only possible in a safe state and, on the outside of the housing, there is provided at least one keyboard and observation station for locally checking the complete system.
The invention is very economical, particularly as a result of the small housing. The analyzer system can be completely assembled and tested in the factory, so that only minimum inspection and assembly expenditure is necessary at the point of installation. The dimensions also make it possible, in most cases, to find an installation point close to the process, so that no long and therefore costly supply and discharge lines, or process return and pressure raising means are required. The invention provides the advantage that explosion and weather protection can be achieved with a single housing, so that an explosionproof zone is formed within the housing. Thus, an explosion protection is provided by the housing, this need not be achieved through the construction of the analyzers, so that the latter can have standard designs. As a result the operating staff require no special training and no special spares or tools are required for maintenance purposes.
In addition, an optimum protection against hazardous materials is achieved. As the housing can be tightly closed and as only, a relatively small scavenging quantity is necessary, it is possible to provide washing and scavenging cycles through using a self-sufficient circulation. Therefore highly effective inert gases can be used and also a largely self-sufficient auxiliary material supply can be achieved. It is also possible to minimize the manufacturing and operating costs for air conditioning of the housing interior.
Another important advantage of the invention is the compact construction of the analyzer system when the housing is closed. However, optimum accessibility is ensured for replacement, repairing and maintaining units if the support member is extended from the housing.
Another important advantage of the invention is the high availability of the analyzer system. Practical tests have revealed that a 90% availability can be achieved. This is brought about in that the "explosion-free" atmosphere in which all the units are housed permits the use of standard sensors in a virtually random number. It is also possible to arrange even extensive electronic evaluation units within the housing, without any restriction being required with respect to explosion protection. With the aid of an electronic fault diagnosis system, function monitoring and fault detection can take place with the housing closed. There can also be a data teletransmission of the diagnosis data to a central station and a continuous monitoring of the test signals for plausibility and error limits. A fault diagnosis system reduces the repair times, in which is normally included error detection and location. In addition, minimum demands are made on the diagnosis staff.
Tried and tested measuring methods and equipment can be used in the design of the fault diagnosis system. There is no restriction to equipment which just happens to be available in an explosionproof version. There are no technical and commercial restrictions regarding the arrangement and routing of lines, because inexpensive standard constructions can be used.
Availability is also increased in that a rapid replacement of complete analyzer systems is possible, e.g. for carrying out a major overhaul in a workshop. To this end, it is merely necessary to remove the door member and the support member connected thereto and replace same by another. Systematic errors and faults in the units are reduced by inner area air conditioning. Any chance faults which occur are immediately detected and indicated by the fault diagnosis system.
The explosion-protected inner area offers the possibility of providing freely selectable analyzer combinations. This has the advantage that improved combinatory measuring methods can be performed and that correlative and redundant measurements can be carried out. The invention also offers many advantages regarding the protection of operating personnel and the environment. Through the locking of the door member combined with the monitoring means access to the interior of the housing is controlled in such a way that opening is prevented in a dangerous state. Thus, maintenance can also be carried out by untrained staff and the explosion protection is independent of the care exercised by servicing staff. As a result of the very tight, insulating housing the requirements for a circulation of the internal gas volume are satisfied. It is possible without difficulty to use the protection types "external ventilation" and "overpressure encapsulation" for the entire housing. In the case of economic use, these protection types offer the minimum use restrictions. Through the use of inert gases for scavenging purposes and as an ignition protection, there is no risk of saturation with flammable gases. The pressure-tight housing requires minimum ignition protection gas quantities. There is also no need for permanent scavenging and compensation of leakage losses. As a result of a slight overpressure in the inner area, it is possible to prevent any penetration of the external atmosphere.
When using an ignition protection gas, it is also possible to construct cooling or heating means with non-explosionproof designs. If a self-sufficient water circulation is provided for analyzer cooling purposes, there is no need for water treatment means of the type required when cooling water has to be taken from external sources.
The circulation of the inert protective gas for avoiding dead corners necessary for explosion protection reasons can be linked in simple manner with air conditioning, so that independently of the particular analyzer system installed, largely in the form of small, complex process systems, as well as environmental conditions, it is possible to ensure a regulated inner area temperature.
The housing also makes it possible to install all auxiliary systems necessary for the operation of an analyzer under the same explosion-protected conditions and independent of environmental conditions, such as cold, heat, corrosion, etc.
With regards to the housing, it is pointed out that protection against explosions, weather and contact with health-prejudicial materials is ensured. As a result of the automatic door, automatic energizing takes place of a testing, switching on and switching off system. The interior of the housing can only be entered by the operator when the programmed safety procedure releases the automatic door system. The analyzer system only starts operating when an adequate explosion protection is ensured in the interior of the housing, i.e. when the units of the entire system are no longer accessible to the operator.
Apart from the economic advantages and the high availability, a further advantage of the invention is the minimizing of accident risks. As the diagnosis system covers all units of the entire analyzer system and as a result of a corresponding redundancy operates clearly and free from inherent errors, it is possible to clearly locate errors within individual units. This prevents opening and closing of the house and putting into operation only being possible when the analyzer system is in a safe state. This includes checking hot surface and electrical equipment for the capacity to ignite a flammable mixture and that inert gas is mixed with oxygen prior to opening the protective housing in order to exclude health hazards. However, prior to putting into operation no atmospheric oxygen must be in the protective housing. As there is no need to separately provide the units with explosion protection means, there is no need to handle such means. Thus, there is no risk that e.g. on closing the pressure-tight encapsulation or overpressure encapsulations for individual units of operating errors being made which could lead to accidents. There is obviously also no need to take account of assembly-relating regulations when fitting equipment, which would otherwise have to be taken into account, e.g. in the case of the protection type intrinsic safety.